It has recently been estimated that as many as ten million men in the United States alone suffer from chronic erectile impotence, or the inability to maintain an erection of sufficient rigidity or duration to engage in coitus. Of that number approximately eighty-five percent of the cases of chronic erectile impotence are believed to be related to organic, rather than psychological, causes. Many of these organically caused cases of impotence, as well as some of the psychologically rooted cases which have not responded to treatment, are candidates for a penile prosthesis device. In fact, the surgical implantation of penile prostheses has become an increasing accepted technique in the treatment of chronic erectile impotence with approximately 35,000 prostheses being implanted each year.
There are several types of penile prostheses currently available. One type, known as a rigid prosthesis, includes a pair of relatively rigid elongate rods which are implanted into the corpus cavernosum bodies of the penis, which are columns of erectile tissue running the length of the penis. The implanted rods maintain the penis in a constant state of erection, which can be difficult to conceal and embarrassing in some situations. Another type, known as a semi-rigid prosthesis, typically consists of bendable, or malleable, rods which when implanted into the penis, maintain the penis in a manipulated position. While these devices allow manipulation into a variety of positions, they always maintain the girth of an erect penis and still do not simulate flaccidity overly well.
A third type of prosthesis, and by far the most mechanically complex, is an inflatable prosthesis. In this type of device inflatable cylinders are implanted in the corpus cavernosum bodies of the penis with a reservoir implanted in the abdominal cavity and a manual pump implanted in the scrotum. However, the locations of the reservoir and pump may vary, with one Model even including all of the components in the corpus cavernosum. When the pump is actuated, fluid from the reservoir inflates and expands the cylinder thus simulating the girth and rigidity of an erect penis. Opening of a valve allows the fluid in the cylinder to return to the reservoir causing the cylinder to deflate, and thus simulating a normally flaccid penis. These are just examples of the many types of prostheses known.
Regardless of the type of protheses or the mechanical complexity, the various devices all require implantation into the penis and possibly also into the abdominal cavity and the scrotum. Where the prostheses comes into contact with surrounding tissue, smooth surface silicone rubber is generally employed as it is nontoxic, nonreactive, and resistant to wear, and also maintains its functionality for an extended period of time. However, other smooth surfaced materials, such as certain plastics, have also been used.
In response to the presence of an implanted foreign object, the body generally reacts by forming a fibrous pseudocapsule of scar tissue around the object. This pseudocapsule of scar tissue ideally acts to support the implanted prosthetic device, allowing it to function without displacement. However, tissue adherence and tissue ingrowth does not occur around and to the surface of an inert smooth surface device. The scar tissue forming the pseudocapsule has a linear collagen arrangement that can contract and displace the implanted device. Also, because tissue adherence to the device does not occur, periprosthetic dead spaces are created and the implanted device may thus move relative to the host tissue inducing cellular trauma and the accompanying risk of infection. Further, the implanted device may erode the surrounding tissue and eventually cause perforation. The uneven formation of the fibrous scar tissue around the device may also cause contracture of various components of the implant, such as the inflatable cylinders, thus reducing their functionality.
Unfortunately, approximately twenty percent of the patients receiving penile prosthetic devices suffer complications such as mechanical failure of the prostheses or those related to erosion, infection, perforation, contracture, uncontrolled mobility of the device and pain. Most often correction of the complication requires removal of the device, treatment of the affected tissue, and eventual replacement of the prosthesis. With the increasing acceptance of penile prostheses, physicians and manufacturers have attempted to reduce the incidents of complication predominately by improving the mechanical reliability of the devices and by using improved infection fighting drugs.
It would be desirable to provide a prosthetic device which reduced the occurrence of complications.